JPS62141560A - Pretreating liquid for burning and photoengraving method - Google Patents

Abstract

PURPOSE:To eliminate ground stains and to improve the sensitizing characteristic of an image part by applying a pretreating liquid for burning consisting of an aq. soln. contg. a phytic acid and/or the water soluble salt thereof and sulfite on a lithographic printing pate prior to the burning treatment after developing and subjecting said plate to the burning treatment in the presence of said compd. CONSTITUTION:The aq. soln. contg. the phytic acid and/or the water soluble salt thereof and sulfite is applied on the lithographic printing plate prior to the burning treatment after development and is subjected to the burning treatment in the presence of said compd. The content of the phytic acid and/or the water soluble salt thereof in the pretreating liquid for burning is 1-40wt% (hereafter abbreviated as %), more preferably 3-30%. The lithographic printing plate which obviates the generation of the stains in the non-image part, has the high sensitizing characteristic in the image part and has excellent print resisting power is thus obtd.

Description

Detailed Description of the Invention [Field of Application of the Invention] The present invention relates to a photosensitive lithographic printing plate, particularly a photosensitive lithographic printing plate having a metal support, which is subjected to image exposure and development, and then subjected to a burning treatment to produce a lithographic printing plate. Relating to a method of manufacturing.

[Conventional technology]

Lithographic printing is a printing method that skillfully takes advantage of the property that water and oil essentially do not mix. The former is a non-image area and the latter is an image area. Therefore, the photosensitive composition used for preparing a lithographic printing plate is required to have the property of repelling water and accepting oil-based ink after image formation.

There are two types of photosensitive compositions used to create lithographic printing plates: positive type and negative type.
Those made of quinonediazide compounds are widely used.

Positive-working photosensitive lithographic printing plates are made by coating an 0-quinonediazide compound alone or in a mixture with an alkali-soluble resin such as a novolac type phenol resin or cresol resin on a suitable support such as metal or plastic. When exposed to actinic rays through a transparency, the 0-quinonediazide compound in the exposed areas decomposes and becomes alkali-soluble, so it is easily removed by an aqueous alkaline solution to give a positive image. Therefore, when a support having a hydrophilic surface is used, the hydrophilic surface of the support is exposed in the portion removed with the alkaline aqueous solution, and this portion receives water and repels ink. On the other hand, the portion that remains as an image is lipophilic and will absorb ink.

On the other hand, many negative photosensitive compositions use diazonium salts, azide compounds, or photopolymerizable compounds. When a support with a hydrophilic surface is used, the unexposed areas are removed by a developer, exposing the hydrophilic surface of the support, which receives water and repels ink. On the other hand, the portion that hardens upon exposure and remains as an image upon development is lipophilic and receptive to ink.

When the lithographic printing plate created in this way is printed on an offset printing machine, beautiful printed matter can be obtained. Planographic printing plates made from such photosensitive planographic printing plates can produce tens of thousands of beautiful prints by appropriately selecting the composition of the support and the photosensitive layer coated thereon.
In particular, by using a grained and anodized aluminum plate as a support, it is possible to obtain as many as 100,000 beautiful prints.

However, there is also a desire to obtain many more printed sheets from a single printing plate. In such cases, the image area can be strengthened by exposing and developing a photosensitive lithographic printing plate using a metal plate such as aluminum or zinc as a support in the usual way, and then heating it at a high temperature (so-called burning treatment). The method is valid.

That is, by performing the burning process, the number of printed matter that can be obtained from one lithographic printing plate can be increased several times compared to the case where the burning process is not performed.

In addition, when printing with UV-curable ink, low-temperature, dry ink, etc., printing plate + 9 images (special printing ink containing a large amount of components that dissolve particles), the plate is made using the normal method without burning. With printed printing plates, the image area elutes violently, and the number of printed sheets is significantly lower than when using normal ink, but when burned,
Since the solvent resistance of the image area is greatly improved, a sufficient number of prints can be obtained even with the above-mentioned special printing ink.

However, the non-image area of the printing plate (i.e., the area where the hydrophilic support surface is exposed by development), which was hydrophilic before the treatment, loses its hydrophilicity due to the burning process, resulting in Is it bad news for printed materials to cause harm to the public? Dirt (so-called scumming) occurs on the surface.

With heating to a level that does not cause such background smearing, a sharp easing effect cannot be obtained and image reinforcement cannot be achieved. Therefore, the 2!
Surface preparation must be carried out to prevent this. Various proposals have been made in the past as a surface smoothing treatment used before and/or after this burning treatment step.

For example, after the burning process, a process for cleaning the stains generated in the non-image area and restoring hydrophilicity.

Fluoride aqueous solutions such as hydrofluoric acid, 1115 hydrofluoric acid, and hydrosilicofluoric acid are used as liquids, but these fluorides belong to the class of poisonous substances, so they must not be used as a public safety measure. There were many problems.

Furthermore, when this surface smoothing treatment is applied, the metal surface of the support is corroded, making the surface more susceptible to adhesion (l), and also becoming weaker against abrasion. , (hydrophilicity) is lost, background smear occurs, and further printing is not possible.

In addition, as a processing method to prevent the hydrophilicity of the non-image area from decreasing before the burning process, Japanese Patent Laid-Open No. 51
Publication No. 34001 discloses treatment with an aqueous solution of a salt of an organic sulfonic acid, such as sodium alkylnaphthalene sulfonate, sodium alkyldiphenyl ether sulfonate, or lithium nitrate, before burning. Among these, aqueous solutions of salts of organic sulfonic acids such as sodium alkylnaphthalene sulfonate and sodium alkyl diphenyl ether sulfonate have extremely high foaming properties.
It is unsuitable for use in the spray circulation type processors that are currently widely used, and has the disadvantage that it is not possible to automate the plate-making process.

Furthermore, when treated with a solution containing lithium nitrate and burned, the prevention of scumming was insufficient. In addition, the special public
Publication No. 28062 discloses a method of treating with an aqueous solution containing sublimable boric acid and its salts before the burning treatment, and then performing the burning treatment in the presence of the compound.
This method also did not sufficiently prevent scumming. In particular, if the washing with water after the burning process is insufficient,
When a dextrin-based gum solution with weak hydrophilicity is used as the desensitized gum solution, there is a drawback that scumming is likely to occur. Furthermore, JP-A-52-2205 discloses that gum arabic, cellulose ether,
Treatment with aqueous solutions of organic substances such as polyacrylic acid and/or water-soluble inorganic salts such as borates, phosphates, sulfates, halides such as alkali metals and alkaline earth metals has been indicated. Even with this method, it is not always possible to completely prevent background smearing, and especially when using aqueous solutions of water-soluble polymers such as gum arabic and polyacrylic acid, the image area becomes difficult to receive ink during printing. This had the disadvantage of causing poor infilling.

Furthermore, JP-A-57-52057 discloses a method of treating with an aqueous solution containing a carboxyl group-containing amine or a salt thereof such as ethylenediaminetetraacetic acid or hydroxyalkylethylenediaminetriacetic acid before the burning treatment. . However, this method could not be said to be sufficiently effective in preventing background stains.

[Problem that the invention seeks to solve]

An object of the present invention is to provide an improved plate-making method that includes a burning process. More specifically, it is an object of the present invention to provide a plate-making method including a burning process, which can produce a lithographic printing plate that is free from scumming and has excellent oil sensitivity in image areas.

Another object of the present invention is to provide a plate-making method including a burning process, which can be automated by using a large-sized spray circulation processing machine or the like.

Another object of the present invention is to provide a burning treatment liquid that exhibits extremely little discoloration or coloration even after long-term storage.

[Means for solving problems]

An object of the present invention is to use a plate-making method in which a photosensitive lithographic printing plate is subjected to a burning treatment after image exposure and development, in which phytic acid and/or a water-soluble salt thereof and a sulfite are added to the plate before the burning treatment after development. This is achieved by a method characterized by applying an aqueous solution containing the compound (hereinafter referred to as "burning pretreatment liquid") to a lithographic printing plate and performing a burning treatment in the presence of the compound.

The burning pretreatment liquid of the present invention needs to contain free phytic acid and/or a water-soluble salt thereof as one of the active ingredients. Examples of water-soluble salts include alkali metal salts such as sodium salts, potassium salts, and lithium salts, ammonium salts, and amine salts. Specific examples of amine salts include diethylamine, triethylamine, propylamine, dipropylamine, tripropylamine, butylamine, amylamine, hexylamine, laurylamine, ethylenediamine, trimethylenediamine, tetramethylenediamine, pentamethylenediamine, and hexamethylene. Salts of diamine, ethanolamine, jetanolamine, triethanolamine, allylamine, aniline, etc. can be used, but CnHtn++ NHa,'(C
A salt of an amine represented by -H2□1)2Ntl, (C-Hz.1), N [wherein n is 2 to 8 and may be branched] is preferred.

Phytate It may be a water-soluble salt, and may be a normal salt in which all 12 acid hydrogens have been replaced, a hydrogen salt (acidic salt) in which some of the acid hydrogens have been replaced, or a salt of one type of base. Either a simple salt consisting of a salt or a double salt containing a base of 2 m or more as a component can be used in the present invention.

The content of phytic acid and/or its water-soluble salt in the burning pretreatment liquid is preferably 1 to 40 M% (hereinafter abbreviated as %), more preferably 3 to 30%.

Sulfites, which are the other essential components in the burning pretreatment liquid of the present invention, include sodium, potassium, lithium, strontium, cesium, selenium, osmium,
Examples include water-soluble salts such as ammonium and amine salts.

The content of the water-soluble salt is preferably 0.0002 to 0.10%, particularly preferably 0.001 to 0.05%.

Although it is essential that the burning pretreatment liquid of the present invention contains the above-mentioned components, it can further contain various additives. Examples of such additives include surfactants, various salts, acids, alkalis, and the like.

The surfactant helps the pre-burning treatment liquid of the present invention to be uniformly applied to the surface of the lithographic printing plate, and also partially suppresses staining of non-image areas due to the burning process. Preferred surfactants are anionic surfactants, especially those containing sulfonic acid groups such as alkylbenzene sulfonates, alkyldiphenyl ether disulfonates, alkylnaphthalene sulfonates, altehyde condensates of alkylnaphthalene sulfonates, and α-olefin sulfonates. Surfactants, lauryl sulfate,
Sulfate ester surfactants such as polyoxyethylene alkyl ether sulfate and polyoxyethylene alkyl phenyl ether sulfate are particularly preferred. The surfactant is suitably contained in the burning pretreatment liquid in an amount of about 0.05% to about 20%, preferably 0.1 to 10%.
% range.

The pH of the burning pretreatment liquid is desirably adjusted to a range of 2 to 1O1, preferably 3 to 8. This not only allows the burning pretreatment liquid to be handled safely, but also suppresses etching effects on the aluminum support, and further prevents deterioration of the hydrophilicity of the aluminum oxide surface of the support.

Furthermore, the burning pretreatment liquid of the present invention contains gum arabic,
Add water-soluble polymer substances such as dextrin, carboxymethylcellulose, polyacrylic acid, polymethacrylic acid, and salts thereof (e.g., sodium salt), polystyrene sulfonate, color chart, antifoaming agent, preservative, etc. You can also do that.

The burning pretreatment liquid of the present invention is used to image-expose a photosensitive lithographic printing plate, develop it, and wash it with water if necessary, and then removes unnecessary parts for printing with a correction agent, leaving the printing plate with no room for further correction. After preparation, it is dried if necessary and applied to the printing plate before being burnt. The method is as follows: 1. Sponge or absorbent cotton soaked with the pre-treatment liquid. Trowel, applied onto lithographic printing plate or filled with processing solution? There are methods of coating by dipping the printing plate in the coating, coating with a self-coater,
Alternatively, methods such as spraying may be applied.

In addition, more favorable results can be obtained by using a squeegee or squeegee roller to even out the coating amount after coating.

The amount of the burning pretreatment liquid applied to the printing plate can be set arbitrarily, but it is preferably 20 to 100ml per printing plate, preferably 30 to 60ml. mi! It is desirable to do so.

The lithographic printing plate coated with the burning pretreatment liquid is dried if necessary (and then heated to a high temperature with a burning processor (for example, Burning Processor 1300 sold by Fuji Photo Film Co., Ltd.). The temperature and time are preferably in the range of 180 to 300° C. for 1 to 20 minutes, although it depends on the nature of the components used to form the image.

The planographic printing plate subjected to the burning treatment pQ can be subjected to conventional treatments such as washing with water and guttering, as necessary. 1. The plate-making method according to the present invention can be applied to various photosensitive planographic printing plates, but in particular, photosensitive planographic printing plates (printing plates to which photosensitization has been imparted in advance) using an aluminum plate as a support,
called a version. ) can be suitably used for. It takes 2
A preferred version of the 5th edition is, for example, British Patent No. 1.350.
521, a photosensitive layer made of a mixture of a diazo resin (salt of a condensate of p-diazodiphenylamine and paraformaldehyde) and shellac is provided on an aluminum plate, British Patent No. 1 ,460.9
No. 78 and No. 1,505.739, the photosensitive layer is made of a mixture of a diazo resin and a polymer having hydroxyethyl methacrylate units or hydroxyethyl acrylate units as main repeating units. A negative 28 plate, such as one provided on an aluminum plate, and a photosensitive layer consisting of a mixture of an O-quinonediazide photosensitive material and a novolac type phenolic resin, as described in JP-A-50-125.806, are used. Includes 28 positive plates mounted on aluminum plates. Further, there is a PS plate in which a photosensitive layer of a photocrosslinkable photopolymer is provided on an aluminum plate as specifically shown in US Pat. No. 3,860,426, and US Pat. No. 4.0.
PS plate in which a photosensitive layer of a photopolymerizable photopolymer composition as described in Patent Nos. 72.528 and 4.072.527 is provided on an aluminum plate, British Patent No. 1, 235 .281 and 1.495.86
Also preferred is a PS plate in which a photosensitive layer made of a mixture of azide and a water-soluble polymer is provided on an aluminum plate as described in each specification of No. 1. Among these PS plates, a particularly preferable PS plate to be subjected to the plate making method of the present invention is O-
It is a positive type 28 plate having a photosensitive layer made of a naphthoquinonediazide compound and a novolac resin, and is published in US Pat. No. 4.
This is explained in detail in the specification of No. 259.434, column 3, line 2 from the bottom to column 6, line 14.

〔Effect of the invention〕

According to the plate making method of the present invention, there is no need to perform a surface smoothing treatment after the burning treatment. □Despite this, a lithographic printing plate with no staining in the non-image area, high oil sensitivity in the image area, and excellent printing durability can be obtained. Moreover, since the burning pretreatment liquid of the present invention has low foaming properties, it can be applied to lithographic printing plates using a spray circulation type processing machine, making it possible to automate the plate-making process, as well as being stable over time and causing no discoloration. There are great advantages such as not having to do this.゛[Example] The present invention will be explained in more detail below with reference to Examples.

Example 1 Naphthoquinone-(1) of 1.5-dihydroxynaphthalene
, 2)-Diazide (2)-5-sulfonic acid ester (2 parts by weight) and 4 parts by weight of novolak type talesol-formaldehyde resin were dissolved in 100 parts by weight of ethylene glycol monomer □'' thyl ether. 24mm
This solution was applied to a grained aluminum plate at a weight of 2.5 g/m'' after drying. After being brought into close contact with each other and exposed for 30 seconds with a 3KW metal halide lamp from a distance of 1m, the samples were developed by immersing them in a 5% by weight sodium silicate aqueous solution for about 1 minute.After washing with water, they were subjected to a pre-burning treatment with the following composition. Pour the liquid onto a printing plate of 1 m
'40m'l per hit! Apply and dry.

○ Burning pretreatment liquid phytic acid (50% aqueous solution) 60 parts by weight Potassium hydroxide 20 Sodium sulfite 3 Sulfanilic acid
...77 Isopropylnaphthalene sulfonic acid sorter book...3 Pure water...837
The printing plate thus treated was heated in a commercially available burning processor at a temperature of 260° C. for 6 minutes.

After cooling, it was gummed, and when this printing plate was attached to an offset printing machine and printed, beautiful prints were obtained after just a few sheets, and when printing was continued, 150,000 beautiful prints were obtained.

Comparative Example 1 A lithographic printing plate treated under exactly the same conditions as in Example 1 up to the development process was treated with 4% by weight ammonium borate instead of the bar erasure pre-processing solution used in Example 1, and subjected to the same burning process. and gum pulling. When this lithographic printing plate was used for printing, smearing occurred in the halftone dot image in a portion of the shadow from the beginning of printing, and it was necessary to remove the dirt from the smeared area with a plate cleaner.

Example 2 The same method as in Example 1 was placed on a 0.311 m thick aluminum plate that had been grained and anodized (anodized in 15 wt% sulfuric acid at a current density of 1.6 amperes/dm for 2 minutes). A positive photosensitive lithographic printing plate was prepared by coating the photosensitive liquid.

A transparency was attached to this and exposed for 40 seconds from a distance of 1 m using a 3KM metal halide lamp, and then developed by immersing it in a 7% by weight aqueous solution of sodium silicate for about 1 minute.

This lithographic printing plate is processed using an automatic through-type burning processor [
Manufactured by Process Materials Co., Ltd. Continuously processes Asahi Risui application, burning, and gumming before burning. ] to form a continuous ring. Here, the burning temperature was set at 150 t for preheating and 240° C. for postheating, the passage time through the furnace was about 3 minutes, and the following composition of the burning pretreatment liquid was used. Incidentally, the burning pretreatment liquid was applied in an amount of 50 mji per printing plate IIrL''.

(50% aqueous solution of phytic acid) 60 parts by weight Lithium hydroxide 18 Sodium sulfite 4 Diphenyl ether disulfide 18 Sodium phonate (Product name: Sandeft BL (manufactured by Sanyo Chemical Co., Ltd.)) Pure water...900
When the lithographic printing plate obtained by the burning process was directly attached to an offset printing machine and printed, beautiful prints were obtained in just a few prints, and 300,000 prints were obtained by continuing the printing process.

Example 3 In the same manner as in Example 1, except that an aqueous solution having the following composition was used as the burning pretreatment liquid, the same results as in Example 1 were obtained.

○ Burning pre-treatment liquid (50% aqueous solution of phytic acid)...60 parts by weight Monoethanolamine...20 Sulfanilic acid...60 Para-toluenesulfonic acid φ-...3 Potassium sulfite
... 3 Polystyrene sulfonic acid ...
10 Potassium (25%) (Product name manufactured by Toyo Soda Co., Ltd., PS-5) Naphthalene sulfonic acid 2 Formalin condensate (Product name (Demol NL Kao Atlas Co., Ltd.) Polyoxyethylene alkyl ...-2 Sodium phenol ether sulfate (trade name: Repenol WZ Kao Atlas Co., Ltd.) Pure water ...84 o
Example 4 Polyhydroxyphenyl and naphthoquinone-1,2- obtained by condensation polymerization of acetone and pyrogallol as described in Example 1 of U.S. Pat. No. 3,635,709
Grained and anodized aluminum plate used in Example 2 by dissolving 4 parts by weight of diazide (2)-5-sulfonic acid ester and 4 parts by weight of novolac type cresol formaldehyde resin in 100 parts by weight of ethylene glycol monomethyl ether. dry weight 2.5 g/m”
A positive photosensitive lithographic printing plate was prepared.

After this positive photosensitive lithographic printing plate was exposed, developed and washed with water under the same conditions as in Example 1, a burning pretreatment liquid having the following composition was applied, and then a burning treatment was performed at 260° C. for 5 minutes.

0 Pre-burning ripening liquid Phytic acid (50% aqueous solution)...50 Heavy items Sodium hydroxide...15 Potassium citrate...10 Gum arabic
・・・・・・ 3 Lithium sulfite ・
... 2 Sodium sulfite ...
3 Sulfanilic acid...-20 Sodium alkylsulfonate...10 (Product name Bionin A-32 Takemoto Yushi Co., Ltd.) Pure water...887
When the resulting lithographic printing plate was mounted on an offset printing machine without gumming and printed, beautiful prints were obtained in just a few prints, and 200,000 prints were obtained by continuing the printing process.

Example 5 A solution was prepared by dissolving 20 parts by weight of shellac and 3 parts by weight of a diazo resin obtained by condensing p-)luenesulfonate of p-diazodiphenylamine with formaldehyde in 80 parts by weight of dimethylformamide. On the other hand, a grained aluminum plate was heated at 80°C with 0.2% potassium zirconium fluoride.
After being immersed in an aqueous solution for 3 minutes to make it hydrophilic,
Wash with water, dry, and add the above prepared solution to a weight of 2.0g after drying.
/rn''.

The negative photosensitive lithographic printing plate thus obtained was exposed through a transparent negative for 30 seconds from a distance of 1 m using a metal halide lamp, immersed in an aqueous solution of 20% by weight of isopropyl alcohol for about 1 minute, and then washed with absorbent cotton. When the surface was lightly rubbed with a cloth, only the unexposed areas were peeled off cleanly and the support surface was exposed.

After washing with water, apply the burning pretreatment liquid used in Example 1,
After drying and performing noening rolling under the same conditions as in Example 1, it was attached to an offset printing machine and printed. Beautiful prints were obtained in about 10 sheets from the start of printing, and when printing continued as it was, the printing started. We were able to obtain 150,000 copies of printed matter that were almost the same.

Example 6 Grinding with pumice/water slurry and a nylon brush, anodizing (anodizing in 20% sulfuric acid at 2 A/dm for 2 minutes), followed by 2.5 ml of sodium silicate at 70°C. An aluminum, mini-lamb plate with a thickness Q of 3 mm was prepared by treating it with a wt% aqueous solution for 1 minute. 8 A photosensitive solution having the following composition was applied to this aluminum plate to give a dry weight of 2.0 g/rn. ”.

○Photosensitive liquid 2-hydroxyethyl methacrylate 5.0g rate/
Acrylonitrile/ethyl methacrylate/methacrylic acid = 37/34/22/7 (weight ratio) copolymer p-diazodiphenylamine 0.5 g p-toluenesulfonate Diazo resin Victoria Pure Blue 0.1 g BOH condensed with formaldehyde
(Manufactured by Odugaya Chemical Co., Ltd.) Methyl cellosolve 95ml/water
5ml
The negative photosensitive lithographic printing plate thus obtained was exposed through a transparent negative to a 3KII metal halide lamp from a distance of 1 m for 30 seconds, and developed using the following developer.

O developer benzyl alcohol 39mj! Jetanolamine 10g Sodium sulfite
5g isopropylnaphthalene
10g sodium sulfonate water
11 After washing with water, apply the burning pre-treatment liquid used in Example 2, dry it, perform the burning treatment under the same conditions as Example 2, and then install it on an offset printing machine and print. You can get beautiful prints with just one sheet,
When they continued printing, they were able to obtain 900,000 prints that were almost the same as the first print.

Example 7 In the same manner as in Example 6, the following photosensitive solution was applied to a plate that had been anodized and treated with sodium silicate in a grain chamber at a dry explosion weight of 13.
It was coated at a concentration of 0 g/m and dried at 100°C for 2 minutes.

○Photosensitive liquid Methyl methacrylate/methacrylic acid 56g Ruric acid (mole ratio 85/15, MEK solution, intrinsic viscosity at 30ti: 0.166) Tri, methylolpropane) 177 40g Acrylate 3-methyl-2-benzoinome 5g Tylene naphtho (1 -2-d) Thiazole However, beautiful prints were obtained after just a few prints.

Example 8 It was confirmed that by adding sulfite to phytic acid, the pre-burning release liquid would not change color even after long-term storage, and that it would not stain the non-image area when used for burning processing. For this purpose, we conducted the following tests.

Burning pre-treatment liquid phytic acid (50%) Sodium sulfite as shown in the table below
As shown in the table below, use potassium hydroxide to pH 5.5~
5. Dilute the total amount to 1. with purified water prepared in 7. It was o i.

The color change property of this burning pretreatment liquid was 9 (40 in Lt').
After storage for a period of time, the test was carried out visually and by measuring the absorbance of 350nfl. In addition, the paper was subjected to a burning process using the processing solution after storage, and printed on an offset printing machine to check for stains in non-image areas. The results are shown in the table below.

Claims (2)

[Claims] (1) A burning pretreatment liquid for lithographic printing plates comprising an aqueous solution containing phytic acid and/or a water-soluble salt thereof and a sulfite. (2) In a plate-making method in which a photosensitive lithographic printing plate is subjected to image exposure and development and then subjected to a burning treatment, a pre-burning treatment consisting of an aqueous solution containing phytic acid and/or a water-soluble salt thereof and a sulfite is performed before the burning treatment after development. A plate-making method characterized by applying a solution to a lithographic printing plate and performing a burning treatment in the presence of the compound.